Two-level led security light with motion sensor

ABSTRACT

A two-level LED security light with a motion sensor. At night, the LED is turned on for a low level illumination. When the motion sensor detects any intrusion, the LED is switched from the low level illumination to a high level illumination for a short duration time. After the short duration time, the LED security light returns to the low level illumination for saving energy. The LED security light includes a power supply unit, a light sensing control unit, a motion sensing unit, a loading and power control unit, and a lighting-emitting unit. The lighting-emitting unit includes one or a plurality of LEDs which maybe turned-on or turned-off according to the sensing results from the light sensing control unit. When the motion sensing unit detects an intrusion, the illumination of the LED security light can be immediately turned on to the high level to scare away intruder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of patent application Ser. No.15/393,768, filed on Dec. 29, 2016 and currently pending. applicationSer. No. 15/393,768 is a continuation of patent application Ser. No.15/213,595 filed on Jul. 19, 2016, issued as U.S. Pat. No. 9,622,328 onApr. 11, 2017; which was a continuation of patent application Ser. No.14/478,150 filed on Sep. 5, 2014, issued as U.S. Pat. No. 9,445,474 onSep. 13, 2016; which was a continuation of patent application Ser. No.13/222,090, filed Aug. 31, 2011, issued as U.S. Pat. No. 8,866,392 onOct. 21, 2014.

BACKGROUND 1. Technical Field

The present disclosure relates to a lighting apparatus, in particular,to a two-level security LED light with motion sensor

2. Description of Related Art

Lighting sources such as the fluorescent lamps, the incandescent lamps,the halogen lamps, and the light-emitting diodes (LED) are commonlyfound in lighting apparatuses for illumination purpose. Photoresistorsare often utilized in outdoor lighting applications for automaticilluminations, known as the Photo-Control (PC) mode. Timers may be usedin the PC mode for turning off the illumination or for switching to alower level illumination of a lighting source after the lighting sourcehaving delivered a high level illumination for a predetermined duration,referred as the Power-Saving (PS) mode. Motion sensors are often used inthe lighting apparatus for delivering full-power illumination thereoffor a short duration when a human motion is detected, then switchingback to the PS mode. Illumination operation controls such asauto-illumination in accordance to the background brightness detection,illumination using timer, illumination operation control using motionsensing results (e.g., dark or low luminous power to fully illuminated),and brightness control are often implemented by complex circuitries. Inparticular, the design and construction of LED drivers are still of acomplex technology with high fabrication cost.

Therefore, how to develop a simple and effective design method onillumination controls such as enhancing contrast in illumination andcolor temperature for various types lighting sources, especially thecontrols for LEDs are the topics of the present disclosure.

SUMMARY

An exemplary embodiment of the present disclosure provides a two-levelLED security light with motion sensor which may switch to high levelillumination in the Power-Saving (PS) mode for a predetermined durationtime when a human motion is detected thereby achieve warning purposeusing method of electric current or lighting load adjustment.Furthermore, prior to the detection of an intrusion, the LED securitylight may be constantly in the low level illumination to save energy.

An exemplary embodiment of the present disclosure provides a two-levelLED security light including a power supply unit, a light sensingcontrol unit, a motion sensing unit, a loading and power control unit,and a light-emitting unit. The light-emitting unit further includes oneor a plurality of series-connected LEDs; when the light sensing controlunit detects that the ambient light is lower than a predetermined value,the loading and power control unit turns on the light-emitting unit togenerate a high level or a low level illumination; when the lightsensing control unit detects that the ambient light is higher than thepredetermined value, the loading and power control unit turns off thelight-emitting unit; when the motion sensing unit detects a human motionin the PS mode, the loading and power control unit increases theelectric current that flows through the light-emitting unit so as togenerate the high level illumination for a predetermined duration.

Another exemplary embodiment of the present disclosure provides atwo-level LED security light including a power supply unit, a lightsensing control unit, a motion sensing unit, a loading and power controlunit, a light-emitting unit. The light-emitting unit includes aplurality of series-connected LEDs. When the light sensing control unitdetects that the ambient light is lower than a predetermined value, theloading and power control unit turns on a portion or all the LEDs of thelight-emitting unit to generate a low level or a high levelillumination; when the light sensing control unit detects that theambient light is higher than the predetermined value, the loading andpower control unit turns off all the LEDs in the light-emitting unit;when the motion sensing unit detects a human motion in the PS mode, theloading and power control unit turns on a plurality of LEDs in thelight-emitting unit and generates the high level illumination for apredetermine duration. An electric current control circuit is integratedin the exemplary embodiment for providing constant electric current todrive the LEDS in the light-emitting unit.

One exemplary embodiment of the present disclosure provides a two-levelLED security light including a power supply unit, a light sensingcontrol unit, a motion sensing unit, a loading and power control unit,and a light-emitting unit. The light-emitting unit includes a phasecontroller and one or a plurality of parallel-connected alternatingcurrent (AC) LEDs. The phase controller is coupled between the describedone or a plurality parallel-connected ACLEDs and AC power source. Theloading and power control unit may through the phase controller controlthe average power of the light-emitting unit; when the light sensingcontrol unit detects that the ambient light is lower than apredetermined value, the loading and power control unit turns on thelight-emitting unit to generate a high level or a lower levelillumination; when the light sensing control unit detects that theambient light is higher than the predetermined value, the loading andpower control unit turns off the light-emitting unit; when the motionsensing unit detects a human motion in the PS mode, the loading andpower control unit increases the average power of the light-emittingunit thereby generates the high level illumination for a predetermineduration.

According to an exemplary embodiment of the present disclosure, atwo-level LED security light includes a power supply unit, a lightsensing control unit, a motion sensing unit, a loading and power controlunit, and a light-emitting unit. The light-emitting unit includes X highwattage ACLEDs and Y low wattage ACLEDs connected in parallel. When thelight sensing control unit detects that the ambient light is lower thana predetermined value, the loading and power control unit turns on theplurality of low wattage ACLEDs to generate a low level illumination;when the light sensing control unit detects that the ambient light ishigher than a predetermined value, the loading and power control unitturns off the light-emitting unit; when the motion sensor detects anintrusion, the loading and power control unit turns on both the highwattage ACLEDs and the low wattage ACLEDs at same time thereby generatesa high level illumination for a predetermine duration, wherein X and Yare of positive integers.

According to an exemplary embodiment of the present disclosure, atwo-level LED security light with motion sensor includes a power supplyunit, a light sensing control unit, a motion sensing unit, a loading andpower control unit, and a light-emitting unit. The light-emitting unitincludes a rectifier circuit connected between one or a plurality ofparallel-connected AC lighting sources and AC power source. The loadingand power control unit may through the rectifier circuit adjust theaverage power of the light-emitting unit. When the light sensing controlunit detects that the ambient light is lower than a predetermined value,the loading and power control unit turns on the light-emitting unit togenerate a low level illumination; when the light sensing control unitdetects that the ambient light is higher than the predetermined value,the loading and power control unit turns off the light-emitting unit;when the motion sensing unit detects an intrusion, the loading and powercontrol unit increases the average power of the light-emitting unitthereby generates a high level illumination for a predetermine duration.The rectifier circuit includes a switch parallel-connected with a diode,wherein the switch is controlled by the loading and power control unit.

To sum up, a two-level LED security light with motion sensor provided byan exemplary embodiment in the preset disclosure, may executePhoto-Control (PC) and Power-Saving (PS) modes. When operates in the PCmode, the lighting apparatus may auto-illuminate at night and auto turnoff at dawn. The PC mode may generate a high level illumination for apredetermined duration then automatically switch to the PS mode by acontrol unit to generate a low level illumination. When the motionsensor detects a human motion, the disclosed LED security light mayimmediate switch to the high level illumination for a shortpredetermined duration thereby achieve illumination or warning effect.After the short predetermined duration, the LED security light mayautomatically return to the low level illumination for saving energy.

In order to further understand the techniques, means and effects of thepresent disclosure, the following detailed descriptions and appendeddrawings are hereby referred, such that, through which, the purposes,features and aspects of the present disclosure can be thoroughly andconcretely appreciated; however, the appended drawings are merelyprovided for reference and illustration, without any intention to beused for limiting the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present disclosure, and are incorporated in andconstitute a part of this specification. The drawings illustrateexemplary embodiments of the present disclosure and, together with thedescription, serve to explain the principles of the present disclosure.

FIG. 1 schematically illustrates a block diagram of a two-level LEDsecurity light in accordance with an exemplary embodiment of the presentdisclosure.

FIG. 2A illustrates a schematic diagram of a two-level LED securitylight in accordance to the first exemplary embodiment of the presentdisclosure.

FIG. 2B graphically illustrates a timing waveform of a pulse widthmodulation (PWM) signal in accordance to the first exemplary embodimentof the present disclosure.

FIG. 3A illustrates a schematic diagram of a two-level LED securitylight in accordance to the second exemplary embodiment of the presentdisclosure.

FIG. 3B illustrates a schematic diagram of a two-level LED securitylight in accordance to the second exemplary embodiment of the presentdisclosure.

FIG. 4A illustrates a schematic diagram of a two-level LED securitylight in accordance to the third exemplary embodiment of the presentdisclosure.

FIG. 4B illustrates a timing waveform of two-level LED security light inaccordance to the third exemplary embodiment of the present disclosure.

FIG. 5 illustrates a schematic diagram of a two-level LED security lightin accordance to the third exemplary embodiment of the presentdisclosure.

FIG. 6 illustrates a schematic diagram of a two-level LED security lightin accordance to the fourth exemplary embodiment of the presentdisclosure.

FIG. 7 illustrates a schematic diagram of a two-level LED security lightin accordance to the fifth exemplary embodiment of the presentdisclosure.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Reference is made in detail to the exemplary embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or alike parts.

First Exemplary Embodiment

Refer to FIG. 1, which schematically illustrates a block diagram of atwo-level LED security light in accordance to the first exemplaryembodiment of the present disclosure. A two-level LED security light(herein as the lighting apparatus)100 includes a power supply unit 110,a light sensing control unit 120, a motion sensing unit 130, a loadingand power control unit 140, and a light-emitting unit 150. The powersupply unit 110 is used for supplying power required to operate thesystem, wherein the associated structure includes the known AC/DCvoltage converter. The light sensing control unit 120 may be aphotoresistor, which may be coupled to the loading and power controlunit 140 for determining daytime or nighttime in accordance to theambient light. The motion sensing unit 130 may be a passive infraredsensor (PIR), which is coupled to the loading and power control unit 140and is used to detect intrusions. When a person is entering apredetermined detection zone of the motion sensing unit 130, a sensingsignal thereof may be transmitted to the loading and power control unit140.

The loading and power control unit 140 which is coupled to thelight-emitting unit 150 may be implemented by a microcontroller. Theloading and power control unit 140 may control the illumination levelsof the light-emitting unit 150 in accordance to the sensing signaloutputted by the light sensing control unit 120 and the motion sensingunit 130. The light-emitting unit 150 may include a plurality of LEDsand switching components. The loading and power control unit 140 maycontrol the light-emitting unit 150 to generate at least two levels ofillumination variations.

When the light sensing control unit 120 detects that the ambient lightis lower than a predetermined value (i.e., nighttime), the loading andpower control unit 140 executes the Photo-Control (PC) mode by turningon the light-emitting unit 150 to generate a high level illumination fora predetermined duration then return to a low level illumination forPower-Saving (PS) mode. When the light sensing control unit 120 detectsthat the ambient light is higher than a predetermined value (i.e.,dawn), the loading and power control unit 140 turns off thelight-emitting unit 150. In the PS mode, when the motion sensing unit130 detects a human motion, the loading and power control unit 140 mayincrease the electric current which flow through the light-emitting unit150, to generate the high level illumination for a short predeterminedduration. After the short predetermined duration, the loading and powercontrol unit 140 may automatically lower the electric current that flowthrough the light-emitting unit 150 thus have the light-emitting unit150 return to low level illumination for saving energy.

Refer to 2A, which illustrates a schematic diagram of a two-level LEDsecurity light in accordance to the first exemplary embodiment of thepresent disclosure. The light sensing control unit 120 may beimplemented by a light sensor 220; the motion sensing unit 130 may beimplemented by a motion sensor 230; the loading and power control unit140 may be implemented by a microcontroller 240. The light-emitting unit250 includes three series-connected LEDs L1˜L3. The LEDs L1˜L3 isconnected between a DC source and a transistor Q1, wherein the DC sourcemay be provided by the power supply unit 110. The transistor Q1 may bean N-channel metal-oxide-semiconductor field-effect-transistor (NMOS).The transistor Q1 is connected between the three series-connected LEDsL1˜L3 and a ground GND. The loading and power control unit 140implemented by the microcontroller 240 may output a pulse widthmodulation (PWM) signal to the gate of transistor Q1 to control theaverage electric current. It is worth to note that the electriccomponents depicted in FIG. 2A only serves as an illustration for theexemplary embodiment of the present disclose and hence the presentdisclosure is not limited thereto.

Refer to FIG. 2B concurrently, which graphically illustrates a timingwaveform of a pulse width modulation (PWM) signal in accordance to thefirst exemplary embodiment of the present disclosure. In the PC mode,the PWM signal may be used to configure the transistor Q1 to have theconduction period T_(on) being longer than the cut-off period T_(off).On the other hand in the PS mode, the PWM signal may configure thetransistor Q1 to have the conduction period T_(on) being shorter thanthe cut-off period T_(off) . In comparison of the illumination levelsbetween the PC and PS modes, as the conduction period T_(on) oftransistor Q1 being longer under the PC mode, therefore have higheraverage electric current driving the light-emitting unit 250 therebygenerate high illumination, which may be classified as the high levelillumination; whereas as the conduction period T_(on) of transistor Q1is shorter in the PS mode, therefore have lower average electric currentdriving the light-emitting unit 250 thereby generate low illumination,which may be classified as the low level illumination.

The microcontroller 240 turns off the light-emitting unit 250 during theday and activates the PC mode at night by turning on the light-emittingunit 250 to generate the high level illumination for a shortpredetermined duration then return to the low level illumination therebyentering the PS mode. When the motion sensor 230 detects a human motionin the PS mode, the light-emitting unit 250 may switch to the high levelillumination for illumination or warning application. The light-emittingunit 250 may return to the low level illumination after maintaining atthe high level illumination for a short predetermined duration to saveenergy.

In addition, the microcontroller 240 is coupled to a time setting unit260, wherein the time setting unit 260 may allow the user to configurethe predetermined duration associated with the high level illuminationin the PC mode, however the present disclosure is not limited thereto.

Second Exemplary Embodiment

Refer again to FIG. 1, wherein the illumination variations of thelight-emitting unit 150 may be implemented through the number oflight-source loads being turned on to generate more than two levels ofillumination. The lighting apparatus 100 in the instant exemplaryembodiment may be through turning on a portion of LEDs or all the LEDsto generate a low and a high level of illuminations.

Refer to FIG. 3A concurrently, which illustrates a schematic diagram ofa two-level LED security light 100 in accordance to the second exemplaryembodiment of the present disclosure. The main difference between FIG.3A and FIG. 2A is in the light-emitting unit 350, having threeseries-connected LEDs L1˜L3 and NMOS transistors Q1 and Q2. The LEDsL1˜L3 are series connected to the transistor Q1 at same time connectedbetween the DC source and a constant electric current control circuit310. Moreover, transistor Q2 is parallel connected to the two endsassociated with LEDs L2 and L3. The gates of the transistors Q1 and Q2are connected respectively to a pin PC and a pin PS of themicrocontroller 240. The constant electric current control circuit 310in the instant exemplary embodiment maintains the electric current inthe activated LED at a constant value, namely, the LEDs L1˜L3 areoperated in constant-current mode.

Refer to FIG. 3A, the pin PC of the microcontroller 240 controls theswitching operations of the transistor Q1; when the voltage level of pinPC being either a high voltage or a low voltage, the transistor Q1 mayconduct or cut-off, respectively, to turn the LEDs L1˜L3 on or off. Thepin PS of the microcontroller 240 controls the switch operations of thetransistor Q2, to form two current paths 351 and 352 on thelight-emitting unit 350. When the voltage at the pin PS of themicrocontroller 240 is high, the transistor Q2 conducts, thereby formingthe current path 351 passing through the LED L1 and the transistor Q2;when the voltage at the pin PS being low, the transistor Q2 cuts-off,thereby forming the current path 352 passing through all the LEDs L1˜L3.The microcontroller 240 may then control the switching operation of thetransistor Q2 to turn on the desired number of LEDs so as to generate ahigh or a low level illumination.

When light sensor 220 detects that the ambient light is higher than apredetermined value, the microcontroller 240 through the pin PC outputsa low voltage, which causes the transistor Q1 to cut-off and turns offall the LEDs L1˜L3 in the light-emitting unit 350. Conversely, when thelight sensor 220 detects that the ambient light is lower than thepredetermined value, the microcontroller 240 activates the PC mode,i.e., outputting a high voltage from pin PC and a low voltage from pinPS, to activate the transistor Q1 while cut-off the transistor Q2,thereby forming the current path 352, to turn on the three LEDs L1˜L3 inthe light-emitting unit 350 so as to generate the high levelillumination for a predetermined duration. After the predeterminedduration, the microcontroller 240 may switch to the PS mode by havingthe pin PC continue outputting a high voltage and the pin PS outputtinga high voltage, to have the transistor Q2 conducts, thereby forming thecurrent path 351. Consequently, only the LED L1 is turned on and the lowlevel illumination is generated.

When the motion sensor detects a human motion in the PS mode, the pin PSof the microcontroller 240 temporarily switches from the high voltage toa low voltage, to have the transistor Q2 temporarily cuts-off thusforming the current path 352 to activate all the LEDs in thelight-emitting unit 350, thereby temporarily generates the high levelillumination. The light-emitting unit 350 is driven by a constantelectric current, therefore the illumination level generated thereof isdirectly proportional to the number of LEDs activated. FIG. 3Billustrates another implementation for FIG. 3A, wherein the relays J1and J2 are used in place of NMOS transistors to serve as switches. Themicrocontroller 240 may control the relays J2 and J1 through regulatingthe switching operations of the NPN bipolar junction transistors Q4 andQ5. Moreover, resistors R16 and R17 are current-limiting resistors.

In the PC mode, the relay J1 being pull-in while the relay J2 bounce offto have constant electric current driving all the LEDs L1˜L3 to generatethe high level illumination; in PS mode, the relays J1 and J2 bothpull-in to have constant electric current only driving the LED L1 thusthe low level illumination may be thereby generated. Furthermore, whenthe motion sensor 230 detects a human motion, the pin PS of themicrocontroller 240 may temporarily switch from high voltage to lowvoltage, forcing the relay J2 to temporarily bounce off and the relay J1pull-in so as to temporarily generate the high level illumination.

The LED L1 may adopt a LED having color temperature of 2700K while theLEDs L2 and L3 may adopt LEDs having color temperature of 5000K in orderto increase the contrast between the high level and the low levelilluminations. The number of LEDs included in the light-emitting unit350 may be more than three, for example five or six LEDs. The transistorQ2 may be relatively parallel to the two ends associated with aplurality of LEDs to adjust the illumination difference between the highand the low illumination levels. Additionally, the light-emitting unit350 may include a plurality of transistors Q2, which are respectivelycoupled to the two ends associated with each LED to provide morelighting variation selections. The microcontroller 240 may decide thenumber of LEDs to turn on in accordance to design needs at differentconditions. Based on the explanation of the aforementioned exemplaryembodiment, those skills in the art should be able to deduce otherimplementation and further descriptions are therefore omitted.

Third Exemplary Embodiment

Refer back to FIG. 1, wherein the light-emitting unit 150 may include aphase controller and one or more parallel-connected alternating current(AC) LEDs. The phase controller is coupled between the described one ormore parallel-connected ACLEDs and AC power source. The loading andpower controller 140 in the instant exemplary embodiment may through thephase controller adjust the average power of the light-emitting unit 150so as to generate variations in the low level and the high levelilluminations.

Refer to FIG. 4A, which illustrates a schematic diagram of a two-levelLED security light 100 in accordance to the third exemplary embodimentof the present disclosure. The main difference between FIG. 4A and FIG.3 is in that the light-source load is an ACLED, which is coupled to theAC power source, and further the light-emitting unit 450 includes aphase controller 451. The phase controller 451 includes a bi-directionalswitching device 452, here, a triac, a zero-crossing detection circuit453, and a resistor R. The microcontroller 240 turns off thelight-emitting unit 450 when the light sensor 220 detects that theambient light is higher than a predetermined value. Conversely, when thelight sensor 220 detects that the ambient light is lower than thepredetermined value, the microcontroller 240 activates the PC mode byturning on the light-emitting unit 450. In the PC mode, themicrocontroller 240 may select a control pin for outputting a pulsesignal which through a resistor R triggers the triac 452 to have a largeconduction angle. The large conduction angle configures thelight-emitting unit 450 to generate a high level illumination for apredetermined duration. Then the microcontroller 240 outputs the pulsesignal for PS mode through the same control pin to trigger the triac 452to have a small conduction angle for switching the light-emitting unit450 from the high level illumination to the low level illumination ofthe PS mode. Moreover, when the motion sensor 230 (also called motionsensing unit) detects a human motion in the PS mode, the microcontroller240 temporarily outputs the PC-mode pulse signal through the samecontrol pin to have the light-emitting unit 450 generated the high levelillumination for a short predetermined duration. After the shortpredetermined duration, the light-emitting unit 450 returns to the lowlevel illumination.

In the illumination control of the ACLED, the microcontroller 240 mayutilize the detected zero-crossing time (e.g., the zero-crossing time ofan AC voltage waveform) outputted from the zero-crossing detectioncircuit 453 to send an AC synchronized pulse signal thereof which maytrigger the triac 452 of the phase controller 451 thereby to change theaverage power input to the light-emitting unit 450. As the ACLED has acut-in voltage V_(t) for start conducting, thus if the pulse signalinaccurately in time triggers the conduction of the triac 452, then theinstantaneous value of AC voltage may be lower than the cut-in voltageV_(t) of ACLED at the trigger pulse. Consequently, the ACLED may resultin the phenomenon of either flashing or not turning on. Therefore, thepulse signal generated by the microcontroller 240 must fall in a propertime gap behind the zero-crossing point associated with the ACsinusoidal voltage waveform.

Supposing an AC power source having a voltage amplitude V_(m) andfrequency f, then the zero-crossing time gap t_(D) of the trigger pulseoutputted by the microcontroller 240 should be limited according tot_(o)<t_(D)<1/2 f−t_(o) for a light-source load with a cut-in voltageV_(t), wherein t_(o)=(1/2πf)sin⁻¹(V_(t)/V_(m)). The described criterionis applicable to all types of ACLEDs to assure that the triac 452 can bestably triggered in both positive and negative half cycle of the ACpower source. Take ACLED with V_(t)(rms)=80V as an example, andsupposing the V_(m)(rms)=110V and f=60 Hz , then t_(o)=2.2 ms and(1/2f)=8.3 ms may be obtained. Consequently, the proper zero-crossingtime gap t_(D) associated with the phase modulation pulse outputted bythe microcontroller 240 which lagged the AC sinusoidal voltage waveformshould be designed in the range of 2.2 ms<t_(D)<6.1 ms .

Refer to FIG. 4B, which illustrates a timing waveform of the two-levelLED security light in accordance to the third exemplary embodiment ofthe present disclosure. Waveforms (a)˜(d) of FIG. 4B respectivelyrepresent the AC power source, the output of the zero-crossing detectioncircuit 453, the zero-crossing delay pulse at the control pin of themicrocontroller 240, and the voltage waveform across the two ends of theACLED in the light-emitting unit 450. The zero-crossing detectioncircuit 453 converts the AC voltage sinusoidal waveform associated withthe AC power source to a symmetric square waveform having a low and ahigh voltage levels as shown in FIG. 4B(b). At the zero-crossing pointof the AC voltage sinusoidal wave, the symmetric square waveform maytransit either from the low voltage level to the high voltage level orfrom the high voltage level to the low voltage level. Or equivalently,the edge of the symmetric square waveform in the time domain correspondsto the zero-crossing point of the AC voltage sinusoidal waveform. Asshown in FIG. 4B(c), the microcontroller 240 outputs a zero-crossingdelay pulse in correspondence to the zero-crossing point of the ACsinusoidal waveform in accordance to the output waveform of thezero-crossing detection circuit 453. The zero-crossing delay pulse isrelative to an edge of symmetric square waveform behind a time gap t_(D)in the time domain. The t_(D) should fall in a valid range, as describedpreviously, to assure that the triac 452 can be stably triggered therebyto turn on the ACLED. FIG. 4B(d) illustrates a voltage waveform appliedacross the two ends associated with the ACLED. The illumination level ofthe light-emitting unit 450 is related to the conduction period t_(on)of the ACLED, or equivalently, the length t_(on) is directlyproportional to the average power inputted to the ACLED. The differencebetween the PC mode and the PS mode being that in the PC mode, the ACLEDhas longer conduction period, thereby generates the high levelillumination; whereas in the PS mode, the ACLED conduction period isshorter, hence generates the low level illumination.

Refer to FIG. 5, which illustrates a schematic diagram of a two-levelLED security light 100 in accordance to the third exemplary embodimentof the present disclosure. The light-emitting unit 550 of the lightingapparatus 100 includes an ACLED1, an ACLED2, and a phase controller 551.The phase controller 551 includes triacs 552 and 553, the zero-crossingdetection circuit 554 as well as resistors R1 and R2. The light-emittingunit 550 of FIG. 5 is different from the light-emitting unit 450 of FIG.4 in that the light-emitting unit 550 has more than one ACLEDs and morethan one bi-directional switching devices. Furthermore, the colortemperatures of the ACLED1 and the ACLED2 may be selected to bedifferent.

In the exemplary embodiment of FIG. 5, the ACLED1 has a high colortemperature, and the ACLED2 has a low color temperature. In the PC mode,the microcontroller 240 uses the phase controller 551 to trigger bothACLED1 and ACLED2 to conduct for a long period, thereby to generate thehigh level illumination as well as illumination of mix colortemperature. In the PS mode, the microcontroller 240 uses the phasecontroller 551 to trigger only the ACLED2 to conduct for a short period,thereby generates the low level illumination as well as illumination oflow color temperature. Moreover, in the PS mode, when the motion sensor230 detects a human motion, the microcontroller 240 may through thephase controller 551 trigger the ACLED1 and ACLED2 to conduct for a longperiod. Thereby, it may render the light-emitting unit 450 to generatethe high level illumination of high color temperature and to producehigh contrast in illumination and hue, for a short predeterminedduration to warn the intruder. Consequently, the lighting apparatus maygenerate the high level or the low level illumination of different hue.The rest of operation theories associated with the light-emitting unit550 are essentially the same as the light-emitting unit 450 and furtherdescriptions are therefore omitted.

Fourth Exemplary Embodiment

Refer to FIG. 6, which illustrates a schematic diagram of a two-levelLED security light 100 in accordance to the fourth exemplary embodimentof the present disclosure. The light-emitting unit 150 of FIG. 1 may beimplemented by the light-emitting unit 650, wherein the light-emittingunit 650 includes three ACLED1˜3 having identical luminous power as wellas switches 651 and 652. In which, switches 651 and 652 may be relays.The parallel-connected ACLED1 and ACLED2 are series-connected to theswitch 652 to produce double luminous power, and of which the ACLED3 isparallel connected to, to generate triple luminous power, and of whichan AC power source is further coupled to through the switch 651.Moreover, the microcontroller 240 implements the loading and powercontrol unit 140 of FIG. 1. The pin PC and pin PS are respectivelyconnected to switches 651 and 652 for outputting voltage signals tocontrol the operations of switches 651 and 652 (i.e., open or close).

In the PC mode, the pin PC and pin PS of the microcontroller 240 controlthe switches 651 and 652 to be closed at same time. Consequently, theACLED1˜3 are coupled to the AC power source and the light-emitting unit650 may generate a high level illumination of triple luminous power.After a short predetermined duration, the microcontroller 240 returns toPS mode. In which the switch 651 is closed while the pin PS controls theswitch 652 to be opened, consequently, only the ACLED3 is connected toAC power source, and the light-emitting unit 650 may thus generate thelow level illumination of one luminous power. In the PS mode, when themotion sensor 230 detects a human motion, the microcontroller 240temporarily closes the switch 652 to generate high level illuminationwith triple luminous power for a predetermined duration. After thepredetermined duration, the switch 652 returns to open status thereby togenerate the low level illumination of one luminous power. The lightingapparatus of FIG. 6 may therefore through controlling switches 651 and652 generate two level illuminations with illumination contrast of atleast 3 to1.

The ACLED1 and ACLED2 of FIG. 6 may be high power lighting sourceshaving color temperature of 5000K. The ACLED3 may be a low powerlighting source having color temperature of 2700K. Consequently, theACLED may generate two levels of illuminations with high illuminationand hue contrast without using a zero-crossing detection circuit.

Fifth Exemplary Embodiment

Refer to FIG. 7, which illustrates a schematic diagram of a two-levelLED security light in accordance to the fifth exemplary embodiment ofthe present disclosure. The light-emitting unit 750 of FIG. 7 isdifferent from the light-emitting unit 640 of FIG. 6 in that the ACLED3is series-connected to a circuit with a rectified diode D and a switch753 parallel-connected together, and of which is further coupled througha switch 751 to AC power source. When the switch 753 closes, the ACelectric current that passes through the ACLED3 may be a full sinusoidalwaveform. When the switch 753 opens, the rectified diode rectifies theAC power, thus only one half cycle of the AC electric current may passthrough the ACLED, consequently the luminous power of ALCED3 is cut tobe half.

The pin PS of the microcontroller 240 synchronously controls theoperations of switches 752 and 753. If the three ACLED1˜3 have identicalluminous power, then in the PC mode, the pin PC and pin PS of themicrocontroller 240 synchronously close the switches 75˜1753 to renderACLED1˜3 illuminating, thus the light-emitting unit 750 generates a highlevel illumination which is three-times higher than the luminous powerof a single ACLED. When in the PS mode, the microcontroller 240 closesthe switch 751 while opens switches 752 and 753. At this moment, onlythe ACLED3 illuminates and as the AC power source is rectified by therectified diode D, thus the luminous power of ACLED3 is half of the ACpower source prior to the rectification. The luminous power ratiobetween the high level and the low level illuminations is therefore 6to 1. Consequently, strong illumination contrast may be generated toeffectively warn the intruder.

It should be noted that the light-emitting unit in the fifth exemplaryembodiment is not limited to utilizing ACLEDs. In other words, thelight-emitting unit may include any AC lighting sources such as ACLEDs,incandescent lamps, or fluorescent lamps.

A lighting apparatus may be implemented by integrating a plurality ofLEDs with a microcontroller and various types of sensor components inthe controlling circuit in accordance to the above described fiveexemplary embodiments. This lighting apparatus may automaticallygenerate high level illumination when the ambient light detected isinsufficient and time-switch to the low level illumination. In addition,when a person is entering the predetermined detection zone, the lightingapparatus may switch from the low level illumination to the high levelillumination, to provide the person with sufficient illumination or togenerate strong illumination and hue contrast for monitoring theintruder.

The above-mentioned descriptions represent merely the exemplaryembodiment of the present disclosure, without any intention to limit thescope of the present disclosure thereto. Various equivalent changes,alternations or modifications based on the claims of present disclosureare all consequently viewed as being embraced by the scope of thepresent disclosure.

What is claimed is:
 1. A two-level LED security light comprising: alight-emitting unit; a loading and power control unit; a light sensingcontrol unit; a motion sensing unit; and a power supply unit; whereinthe light emitting unit is configured with an LED load comprising atleast one LED; wherein the light-emitting unit is angle adjustable toprovide illumination projection for performing security protection;wherein the loading and power control unit comprises a controller and aswitching circuitry, wherein the controller is electrically coupled withthe switching circuitry; wherein the switching circuitry is electricallycoupled with the power supply unit and the light-emitting unit, whereinthe controller outputs a pulse width modulation (PWM) signal to controlthe switching circuitry for delivering different average electriccurrents from the power supply unit to drive the light-emitting unit forgenerating different illuminations, wherein the controller outputs thePWM signal respectively to have a short T_(on) and a long T_(on) in eachduty cycle to control the switching circuitry such that thelight-emitting unit respectively generates at least a low levelillumination and at least a high level illuminations according tosignal(s) received from the light sensing control unit and the motionsensing unit.
 2. A two-level LED security light according to claim 1,wherein a configuration of the light-emitting unit and the power supplyunit is designed to be an adequate LED combination of in parallel and inseries connections such that the average electric current passingthrough each LED of the light-emitting unit remains at an adequate leveland thus a voltage V across each LED of the light-emitting unit complieswith an operating constraint of V_(th)<V<V_(max) featuring electricalcharacteristics of the LED, wherein V_(th) is a minimum thresholdvoltage required to trigger the LED to start emitting light and V_(max)is a maximum operating voltage across the LED to avoid a thermal damageor burning out of LED construction.
 3. A two-level LED security lightcomprising: a light-emitting unit; a loading and power control unit; alight sensing control unit; a motion sensing unit; and a power supplyunit; wherein the light emitting unit is configured with an LED loadcomprising at least one LED; wherein the light-emitting unit isnon-angle adjustable to provide illumination projection along a fixeddirection; wherein the loading and power control unit comprises acontroller and a switching circuitry, wherein the controller iselectrically coupled with the switching circuitry; wherein the switchingcircuitry is electrically coupled with the power supply unit and thelight-emitting unit, wherein the controller outputs a pulse widthmodulation (PWM) signal to control the switching circuitry fordelivering different average electric currents from the power supplyunit to drive the light-emitting unit for generating differentilluminations, wherein the controller outputs the PWM signalrespectively to have a short T_(on) and a long T_(on) in each duty cycleto control the switching circuitry such that the light-emitting unitrespectively generates at least a low level illumination and at least ahigh level illuminations according to signal(s) received from the lightsensing control unit and the motion sensing unit.